Locking device for semitrailers



June 14, 1 938. D 2,120,509.

LOCKING DEVICE FOR SEMITRAILERS Filed May 14, 1937 2 Sheets-Sheet 1 INVENTOR 732 4 2 216} M Fez A TTORNE'Y Patented June 14, 1938 UNITEDSTATES PATENT OFFICE LOCKING DEVICE ron SEMITRATLERS Frederick M. Reid,Detroit, Mich assignorto Fruehaui' Trailer Company, Detroit, Mich., a

corporation of Michigan Application May 14, 1937, Serial No. 142,659 4Claims. I (01. 280-331) a vehicle, such as a tractor. For this purposethe semi-trailer is usually provided with an upper fifth wheelconstruction, and the tractor with a lower fifth wheel construction.The'tractcr is detachable from a semi-trailer and the semitrailer isconventionally provided with a support for holding up the front end ofthe semi-trailer when detached from thetractor, this support being movedout of the way when the tractor and semi-trailer are connected andautomatically moved-into supporting position when the tractor andsemi-trailer are disconnected. A representa tive apparatus of this typeis disclosed'and claimed in my United States Letters Patent No.1,838,868, issued December 29, 1931 on Locking device for semi-trailers.

Apparatus of the type above described in which supporting means for thefront end of the semitrailer are brought into operative position withrespect to the ground when the tractor is disconnected from the traileris-usually provided with a latching device for holding the supportingmeans in operative position. This means usually includes a ratchet typeof device co-operating directly with the supporting device, andadditional means for maintaining the king-pin locking jaws in theirdistended and projected condition 5 in which they are placed as theking-pin on the tractor is finally withdrawn from between them. Thislast mentioned means is not shown in my prior patent above identified,but an equivalent means is shown and described in United States PatentNo. 1,806,191 to A. B. Cadman, issued May 19, 1931 on Trailer vehicle..This last mentioned means has conventionally taken the form of a springpressed device automatically projected between the distended jaws of theking-pin lock when the king-pin is withdrawn from between the jaws.There is one drawback to the conventional type of construction as abovedescribed in that it sometimes occurs that if the tractor is withdrawntoo quickly from the semi-trailer the supporting legs for the front endof the semi-trailer are-moved so quickly toward their operative positionthat they strike an -abutment at the extreme end of their movement andsometimes rebound without becoming latched at that point, and. at

the same time the spring Pl'essed member adapted to maintain theking-pin-jaws in distended position may not act with sufllcient rapiditywith the result that the rebound of the supporting legs effects areverse movement of the king-pin-locking jaws before the member-intendedto main- '5 tain them in spread condition has an opportunity to dropinto place, the result being in such case that the supporting legs foldup and permit the front end of the semi-trailer to drop to the ground.10 Accordingly, it is an object of the present invention to provide aking-p'in locking mechanism for a semi-trailer which is positive inaction; to

provide a structure of the type described that is simple in constructionand economical to manu- 15 facture; to provide a construction of thetype described in which once the king-pin locking jaws are spread totheir distended position by with-' drawal from the king-pin therefromany force transmitted thereto from the supporting legs will 20 act tomore strongly hold the jaws in distended position; and the provision ofa construction of the type described which because of its positiveaction will eliminate the possibility of the supporting legs for thefront end of the semi-trailer 25 from moving'out of their normallylatched supporting relation when once moved thereinto upon withdrawal ofthe tractor from the trailer.

The above being among the objects of the present invention, the sameconsists in certain novel 30 features of construction and combinationsof parts to be hereinafter described with reference to the accompanyingdrawings, andthen claimed, having the above and other objects in view.

In the accompanying drawings which illus- 35 trate suitable embodimentsof the present invention and in which like numerals refer to like partsthroughout the several different views,

Figure 1 is a fragmentary plan view of the front portion of asemi-trailer showing the king-pin 4o locking mechanism andthe'supporting structure for the front end of the. semi-trailer;

Fig. 2 is a side elevational view of a portion of a semi-trailerequivalent to that shown in Fig. 1 shown attached to a portion of atractor;

Fig. 3 is an enlarged fragmentary plan view of the king-pin lockingmechanism shown in the preceding views;

Fig. 4 is a slightly enlarged vertical transverse sectional view takenon the line 4-4 of Fig. 3;

Fig. 5 is a slightly enlarged vertical transverse sectional view takenon the line 5-5 of Fig. 3;

Fig.6 is a view similar to Fig. 3 but illustrating a modified form ofconstruction; and I u Fig. 7 is a slightly enlarged vertical transversesectional view taken on the line 1-1 of Fig. 6.

Referring to the drawings and particularly to Figs. 1 and 2, the trailerincludes a frame or plat.- form I, the rear end of which is supported bywheels (not shown). The forward end of the trailer frame is supported bya tractor 2 through a fifth wheel construction 3. The fifth wheel of thetractor carries a king-pin 5 which is adapted to be engaged by thelocking device carried by the semi-trailer frame. The front end of theframe is provided with a bumper-like member 6 provided with a flaredopen passageway I which leads into a slot 8 extending centrally into thefifth wheel construction 3. These bumper-like members ride over thelower fifth wheel construction of the tractor when it is backed into thesemi-trailer, acting to raise the front end of the semi-trailer, and theking-pin 5 is guided by the side walls of the passageway 1 into the slot8.

The locking device includes-a head I0 reciprocable longitudinally of thesemi-trailer and which carries a pair of locking jaws or members II andI2 eachpivotally secured thereto for movement. about a verticallyextending axis by means of pins Ila and I2a, respectively, located onopposite sides of the longitudinal center-line of the head III. Thisreciprocating head I0 and the two locking members or jaws II and I2reciprocate in unison in an under-cut slideway. This slideway'isprovided by plates I3 and I4 fixed to the trailer frame and upon whichare bolted or riveted brackets I5 and I6. It may be noted that theplates I3 and I4 co-operate to form the slot 8. Secured to the top ofthe brackets are plates I1 and I8 thus forming a pair of under-cutslideways (see Figs. 4 and 5).

The outer end portions of the jaws II and I2 are each provided in their.opposed edges-with a partially circular recess 20 and 22, respectively,which combine when the jaws are in their contracted position asindicated in full lines in Fig.

. 3 to form an approximately circular opening for receiving the king-pin5 therein. Also as noted in Fig. 3 the jaw member II is provided with alug portion 24 projecting across the longitudinal centerline of theslideway in which the jaws are received, at the rear side of the recess20, and the jaw I2 is cut-away to provide clearance for such lug whenthe jaws are in closed position. As will be apparent when the king-pin 5is received between the two jaws I I and I2 and the two jaws arepositioned rearwardly of the front end of the slideway which, therefore,positively prevents them from spreading, the king-pin 5 is positivelylocked with respect to the jaws I I and I 2 and the head I6.

Inorder to lock the jaws I I and I2 against relative movement withrespect to the guideway inwhich they are reciprocable and thereby enablethe tractor and the semi-trailer to be positively locked togetheragainst relative longitudinal movement, a transversely reciprocablelatch member 26 is suitably mounted in a boss 28 formed on the side ofthe bracket I6 and is constantly urged toward projected position bymeans of a coil spring 36. The latch member 26 is automaticallyprojected over the forward end of the jaw member I2 when the jaw memberI2 together with the jaw member I I and head II] are moved to theextremity of their position in a rearward direction, as illustrated inFig. 3. The latch member 26 may be withdrawn in any suitable manner whenit is desired to uncouple the tractor from the semi-trailer, theparticular means shown comprising a rod 32 connected to the latch member26 and, as indicated in Fig. 1,

connected at its opposite end to a bell crank 34 trailer. The oppositeend of the bell crank 34 is connected by a rod 36 to a handle 38conveniently positioned for manual operation.

When it is desired to uncouple the tractor from the semi-trailer, thelatch member 26 is withdrawn by means of the handle 38 and the tractoris moved forwardly, the king-pin 5- being fixed thereto'and movingforwardly with it causing the jaw members II and I2 and the slidablehead ID to move forwardly with the king-pin. During this forwardmovement of the king-pin 5, as soon as the jaw members II and I2 areprojected beyond the forward end of the slideway formed by the bracketsI5 and I6 and co-operating members to such an extent that the slidewayno longer confines the jaw members II and I2 against spreading action,the king-pin 5 acting upon the forward edges of the recesses 20 and 22of the jaw members will tend to spread the jaw members to a sufficientextent to permit the king-pin 5 to be withdrawn therefrom as indicatedin dotted lines in Fig. 3. In order to permit this spreading action ofthe jaw members II and I2 and also to limit the amount which the jawmembers may spread to that only slightly in excess necessary to permitwithdrawal of the king-pin 5, the forward endsof the brackets I5 and I6,

'my prior patent above referred to, such'means are not at all necessaryin accordance with the present invention and may be dispensed withentirely if desired with the construction shown.

In accordance with the present invention, instead of employing springpressed means adapted to be projected between the jaw members II and I2when in projected position as illustrated in the Cadman Patent No.1,806,191 above referred to and as employed in most conventionalconstructions, the forward end of the bracket member I5 adjacent theinner end of the beveled face 40 is provided with an inwardly andforwardly directed tooth 50 and the cut-away portion 44 of the jawmember 'I I is provided with a forward end wall 52 adapted to engageover the forward face of the tooth member 50 in hooked relation theretowhen the jaws II and I2 are withdrawn from their slideway to permit themto be spread sufficiently to permit withdrawal of the king-pin 5 fromtherebetween. Because of the hook-like relation between the forward faceof the tooth 50 and the wall 52, once these parts are brought intoenconstruction inasmuch as the extreme forward ends of the jaw membersII and I2 are inwardly beveled as at 54 so that the king-pin 5, whenmoving rearwardly into engaging relation with respect to the jaw membersHand l2, will force them apart in any event to permit introductionbetween them if the jaw members are in projected position permittingtheir separation.

When the jaw members H and I2 are in the projected position indicated'indotted lines in Fig. 3 and the tractor is backed into the semitrailer,the king-pin 5 will be engaged by the divergent side walls of the slot Iand be guided into the narrow portion 8 thereof where in its rearwardmovement it will strike the projecting end of the lug 24 on the jawmember II at a point, with the relation to its direction of travel, onthe opposite side of the pivot pin I la from the wall 52, and thuspositively turn the jaw member II in a counter-clockwise direction asviewed in Fig. 3 and forcibly disengage the wall 52 from the tooth 58,thereby permitting the jaw member ll to move inwardly towards theking-pin to a position which will permit it to slide rearwardly in theslideway. The jaw member l2, simply through inter-engagement of theforward end of its cut-away portion with the beveled forward end 42 ofthe bracket l5 will in being drawn rearwardly, be pulled into itsoperative position and the two jaw members II and I2 operatively embraceopposite sides of the king-pin 5. Further rearward movement of theking-pin 5 will thereupon cause both jaw members II and I2 and thereciprocablemember ill to move rearwardly in. their slideway until theyreach the position indicated in full lines in Fig. 3 at which time thelatch member 25, which has been depressed by, the jaw member I2 inpassing thereov'er, be pro jected into blocking relation with respect tothe member l2, thereby positively locking the tractor and semi-trailertogether in driving relation.

As indicated in Figs. 1 and 2 the slideable head I8 is connected to theforward end of the longitudinally extending rod member 58 provided withsuitable bearings in one or more of the crossmembers 55. The raisableand lowerable front legs for the semi-trailer include a pair of .wheels58 carried at the ends of an axle member 18. The axle member." inwardlyof each of the wheels 58 is provided with an upwardly projecting leg I2,the upper ends of which are each provided with a bracket member 14. Thebracket members 14 are connected together by a rod or tube 15 theopposite ends of which project outwardly beyond the correspondingbrackets 14 and are slidably received .within the downwardly andforwardly extending slots 18 formed on the inner face of thecorresponding member 88 fixed to the inner face of the longitudinallyextending rails 82 of the semi-tractor frame. The upper end of each slot18 is turned rearwardly and downwardly a slight amount as indicated at84 in Fig. 2 so that when the wheels 58 are in their raised position theends of the cross-bar 15 will' remain seated in the portions 84- underthe force of gravity.

The lower end of the slots 18 are each provided with a pair of adjacentupwardly projecting pocket portions or recesses 85- which when thewheels are in their lowered position-bring the opposite projecting endsof the cross-bar 15 thereinto when the front end of the semi-trailer isdropped a slightamount, so as to hold the wheels in their fullyprojected M position. The wheels 58. are braced in their lower positionby 75 means of a pair of rod members 98 the forward ends of which arefixed to the lower ends of the legs I2 and the rearward and upper endsof which a pair of link members 98' connected at one end thereto extendforwardly therefrom and are pivotally connected. at their forward. endsto the respective brackets 14. AccOldingly, it will be understood thatwhen the rod 68 is moved forwardly from the position'indicated in Figs;1 and 2 in order to uncouple the semi-trailer from the tractor, theupper end of the legs 12 will be moved forwardly and downwardly in theslots 18, thus causing the wheels to be lowered and moving theprojecting ends of the cross-rods 18 into a position to be engaged inthe pockets 86 when the front end of the trailer is loweredas it isreleased from the rear end of 'the tractor. When the tractor backs intothe trailer in order to connect it thereto, the initial movement of theengagement will effect a lifting movement of the front end of thesemi-trailer, thus dropping the projecting ends of the cross-bar 18 outof the corresponding pockets 85 and thence rearward movement of the 'rod58 will cause the wheels 58 to be elevated with the-rest of theirsupporting mechansm.

As previously mentioned, one diihculty experienced with conventionaltypes of constructions of which my prior patent above identified may betaken as an example is that, if the tractor was withdrawn from thesemi-trailer too opportunity to be engaged in the pockets 85, and

at the same time the means employed in conventional constructions fordropping in between the distended king-pin jaws, because of the quick'rebound movement of the rod corresponding to the rebound of the. wheelsor other supporting legs, would fail to function, with the result thatas the tractor pulled out from under the front end of the semi-trailerthe supporting legs would simply fold up into their normally inoperativeposition and permit the front end of the semi-trailer to drop to theground, causing great inconven- 'ienc'e in returning it to its properposition and often causing damage to the semi-trailer and also to thegoods which it might then be carrying. This difliculty in connectionwith the prior structures is effectively prevented by the employment ofthe'present invention inasmuch as soon as the wheels 58 are moved totheir fully projected position the jaw members II and I2 are positivelyspread or distended and the wall 52 is positively moved over the outerface of the tooth 58, so that any tendency of the wheels 68 to reboundand.

engage in the pockets 85 is positively and effectively prevented and,accordingly, inadvertent collapse of the supporting legs is positivelyand simply prevented. Additionally, it will be noted that this positiveeffect is obtained by use of fewer number of parts than in conventionalconstructions inasmuch as the means .employed in conventionalconstructions for spring pressed projection between the distended jawsof the king-pin lock is eliminated.

The trailer may also include mechanism for operatingbrakes on its wheelsand this mechanism may operate through the fifth wheel construction. Forthis purpose the king-pin 5 may be provided with an axially extendingplunger I00, as indicated in Fig. 2, extending therethrough and which isoperable by means of a rod such as I02 which leads to the drivers seat.The plunger I in moving upwardly actuates a member I04 secured to a rockshaft I06 and which is in turn connected to the wheel brakes of thesemitrailer by means of a rod I 0B in a conventional manner.

In Figs. 6 and 'Ta slight .modification of the present invention isshown but inasmuch as all parts thereof with the exception of the jawmembers themselves and the front end of the bracket member I6 isidentical to the construction previously described, all parts except thejaw members are indicated by the same numerals as in the previous views,the jaw members in this case being indicated by the numerals employed inthe previous views except that such numerals bear a prime mark. The onlydifference between the construction shown in Figs. 6 and 7 and thatshown'in the previous views is that both jaw members II{ and I2 areprovided for hook-like engagement with the outer ends of thecorresponding brackets I and I6 when the jaw membrs are in theirdistended or open position. In other words, in this case the jaw memberI2 is provided with a wall 52' corresponding with the wall 52 of the jawmembers II and ;I I and the outer end of the bracket I6 is provided witha tooth member 50', corresponding to-the tooth 50 previouslydescribed,-for co-operating with the jaw member I2 in identically thesame manner. In this case inasmuch as both jaw membersare provided forlocking or hooked engagement with the ends of the respective brackets itis necessary that the lug 24' on the jaw I I be reduced-to half itsthickness and an equivalent lug 24" be provided on the jaw member l2,the lugs 24' and 24" being arranged to lie in overlapping relationshipwith respect to each other to permit proper functioning of the jawmembers. The

broad invention, the scope of which is commensurate with the appendedclaims.

WhatIclaim'is:

P. In a tractor-trailer combination, means forming a slidewaytherebetween, a member movable longitudinally of said slideway, a pairof jaw members pivotally connected to said movable member and .providedwith recesses in their opposed faces adapted for reception and retentionof a king-pin therein, said jaw members being separable when inpartially projected position with respect to said slideflfth wheeldevice, in p b e way whereby to release said king-pin therefrom, andinter-engaging means on-said slideway and one of said jaw'members whensaid jaw member is in opened position forming sole means to positivelylock said movable member against movement inwardly of said slidewayunder the influence of forces applied thereto independently of said jawmembers.

2. In a tractor-trailer fifth wheel structure, in combination,means'forming a slideway, a member movable longitudinally of saidslideway, a pair of jaws pivotally connected to said member for slidingmovement in said slideway and positively maintained against separationwhen fully confined therein, said jaws having matching recesses inopposed edges thereof for reception and retention of a king-pinand-being movable outwardly relatively to one another about theirpivotal axes when in partially projected position with respect to saidslideway whereby to release a king-pin engaged therebetween, andinter-engageable means on one of said jaws and on said means forming ahook-like connection there-. between when said jaw is in opened positionwhereby to positively prevent retractive movement of said jaws in saidslidewayswhen said jaws are in opened position, under the influence offorces acting on said member independently of said jaws tending towithdraw said jaw members into said slideway. V

3. In a semi-trailer structure, in combination. a frame, supportingmeans or one end of said frame movably associated t erewith, means forraising and lowering said supporting means including a longitudinallyreciprocable member and a connection between it and said supportingmeans, a head secured to said longitudinally reciprocable member forreciprocation therewith, means forming a guideway in associated relationwith respect to said head, a pair of jaws movably associated with saidhead and slidably received in said guideway, said jaws being preventedfrom separation with respect to each other when fully confined in saidguideway and having matching recesses formed in opposed faces thereoffor reception and retention of the king-pin, said jaws being separablewith respect to each other when in partially projected relation withrespect to an end of said guideway whereby to release a kingpin confinedbetween them, and inter-engageable means carried by at leastone of saidjaw r'nembers and said guideway forming means interengageable when saidjaws are in opened position forming sole means to positivelypreventwithdrawal of said jaws into said guideway under the influence of forcesapplied thereto through said supporting means.

4. In combination with a semi-trailer, supportingmeans movablyassociated with one end of said trailer and movable between supportingand non-supporting positions, means for moving said supporting meansbetween supporting and non-supporting positions including alongitudinally reciprocable member and a connection between it and saidsupporting means, means forming a slideway, a head on saidlongitudinally member reciprocable therewith a ong said slideway, a pairof .jaws pivotally mounted on' said head and slidably. received in saidslideway, said jaws and slideway being so positively prevented fromseparating movement with respect to each other when fully confined insaid slideway and said jaws being separable with respect to each otherwhen projected from one constructed and arranged that. said jawsare endof said slideway, said jaws having co-operating recesses formed inopposed faces thereof for reception and retention of a king-pin whensaid v opened position forming a sole means to positively preventretracting movement of said jaws in said slideway under the influence offorces transmitted thereto from said supporting means.

FREDERICK M. REID.

